1. Field of the Invention
The present design relates generally to the art of autostereoscopic displays, and more specifically to software techniques for mitigating the effects resulting from differential expansion of a lenticular array and its underlying display.
2. Description of the Related Art
Current autostereoscopic imaging technology, for example the Real D SynthaGram, utilizes an array of Winnek slanted lenticular elements on a display surface as illustrated in FIG. 1 to form a lenticular array. FIG. 1 illustrates a flat-panel display monitor device 101 with a lenticular screen 102 positioned over the flat-panel display monitor device surface. The lenticular screen is configured to direct different components of the autostereoscopic view to different segments of the observer's viewing zone.
Lenticular arrays may also be referred to as a micro-lens array, a lenticular screen, a lens screen, or a lens sheet. The lens sheet, as described by Okoshi in “Three Dimensional Imaging Techniques,” Academic Press, NY, 1976, is constructed using a multiplicity of semi-cylindrical parallel rows of corduroy-like lens elements. In this configuration, software provides an interdigitation mapping technique that operates on multiple perspective image views. This interdigitation mapping technique enables an observer viewing the display to see one of the several left-eye views with his left eye, and one of the several right-eye views with his right eye. This technique enables an observer to view a stereoscopic image or motion picture without the need for special glasses or other selection devices. The observer is not required to wear selection devices because image selection takes place at or close to the plane of the display screen.
A major commercial problem with regard to lenticular arrays has to do with the fact that viewing characteristics, especially the angular extent of the viewing zones, change with the passage of time as the display warms up and reaches steady-state temperature. For example, after being turned on, a display screen and associated lenticular array will increase in temperature, in the course of an hour, from 75 to 105 degrees Fahrenheit. The lenticular array, typically epoxy lenticules coated on a glass substrate, does not expand at the same rate as the display. A liquid crystal display, for example, is a glass chamber filled with liquid crystal material that has associated with it a printed matrix color screen and polarizers. The display and the lens screen are heated as a by-product of illuminating the display, as in the case of a liquid crystal display, or as a result of the inefficiencies of emissive elements as is the case for a plasma display.
Additional heat sources that cause temperature changes over time between initial start-up and steady state operating conditions include heat contributions resulting from other associated electronic functions. At room temperature, the lenticular array lenticules have a specified relative position with respect to the display's pixels. As the lenticular array begins to warm up and reach its steady state operating temperature, the dimensional relationship of the lens sheet and the display changes. This dimensional relationship change produces a repositioning of the lenticules relative to the pixels. Even a minute temperature created shift causes the optical characteristics of the autostereoscopic image to change. These changes in optical characteristics degrade the autostereoscopic image presentation quality when viewed by an observer. As an example, if the interdigitation model employs a pitch value (distance between lenticule aspects, such as distance between maximum points on adjacent lenticules) that is off by only 0.1%, the optimum viewing distance will be substantially altered. In effect the width of the viewing zone is reduced because of this change in pitch making it difficult to find a location in which to view the autostereoscopic image.
With respect to specific temperature effects, when the display is turned on, both the display and the lens sheet begin operation at room temperature and gradually heat up. Current stereoscopic display solutions employ an interdigitation model for use at steady state operating temperature and accept that the autostereoscopic images presented may not be entirely useful until the monitor is fully warmed up. The problem with these current designs is that the angular extent of the viewing zones may be significantly reduced during the warm up period.
Thus it would be advantageous to offer a display design that adjusts for temperature variations affecting the lenticular screen's optical display properties including pitch, offset, and slant relative to the display screen. Adjusting for temperature-related variation in those lenticular screen optical display properties that enter into the interdigitation calculation may allow the highest image quality during the initial warm up period, and throughout the period during which the autostereoscopic monitor is warming up, and finally to maintain optimum performance during steady state operation for long intervals of time. Such an autostereoscopic design may provide for an enhanced viewing experience as compared against previously available designs.